Accelerating a motor can take many steps before achieving a nominal run speed, and depending on the environment, heightened care must be taken during an acceleration of the motor. Control of spindle motors used for spinning discs in a data storage device pose particularly distinct control issues.
Because spindle motors of data storage devices can be operated at velocities of 10K RPM or greater, motor control circuits optimized for operating the spindle motor at the nominal run speed of the spindle motor do not always have the bandwidth to effectively respond to changes in speed of the spindle motor at low speeds. Operating characteristics are very different between 1000 RPM and 10K (or higher) RPM. Such things as the commutation duration, response timing, device-to-device variations in electronics, operating environment including power and temperature differences, and basic physics differences between devices such as inertia and mass play a significant role in how a particular spindle motor accelerates.
While various approaches for compensating variations in motor acceleration during spin up have been proposed, there nevertheless remains a continued need for improvements in the art, and it is to such improvements that the present invention is generally directed.